What is a VPS? I love this one called "My own PC". It doesn't cost like $50/month and it can run more bots than I'd ever want to run!
How to get one? My own, you buy the parts and build, the type everyone else uses, you buy from a site then they give you the connection details.
How to set up multiple bots? Same way you do with each one? Install java, run the .jars.
What is a VPS? A VPS is a Virtual Private Server, it it basically a computer hosted by someone/company somewhere else that costs money to use their system monthly.
How to get one? Google VPS sites, ex; www.seerhost.com
How to set up multiple bots? Once you buy the server you can set them up on the computer thingy.